JC

Jacek Cieslar

Available to hire

I have over a 5 years of experience in designing, developing, and maintaining R/Shiny applications for data exploration, analysis and reporting.

About

I have over a 5 years of experience in designing, developing, and maintaining R/Shiny applications for data exploration, analysis and reporting.
I also build (and maintain) data, analytical and modeling workflows in R and Python.

  • 17 years' experience
  • Joined June 2026

Languages

  • PolishFluent
  • EnglishFluent
  • Spanish; CastilianBeginner

Industry experience

  • Software & Internet
  • Media & Entertainment
  • Professional Services

Work experience· 6 roles

Freelance R/Shiny and Python Developer · Self-EmployedFeb 2026 – Present · 10 mos

Designing, developing and maintaining R/Shiny analytical apps. Building data, analytical and modeling workflows in R/Python. Creating and maintaining R packages and Python modules. Implementing CI/CD pipelines and containerized deployments using Docker.

Software Developer, Senior Data Scientist · Kantar S.A.Oct 2019 – Dec 2024 · 5 yrs 3 mos

Designing, developing and maintaining analytical apps (Shiny), and ETL and data modeling processes (R/Python). Communicating and collaborating with project managers, business analysts and other dev teams. General data science and analytics.

Senior Researcher · ZymetriaDec 2018 – Sep 2019 · 10 mos

Quantitative analysis and reporting. Data processing. Study design and management.

Research Assistant · Institute of Political Studies of the Polish Academy of SciencesSep 2014 – Aug 2017 · 3 yrs
Senior Client Executive, Research Manager · Kantar S.A.Aug 2012 – Dec 2018 · 6 yrs 5 mos
Analyst, Junior Analyst, Intern · Kantar S.A.Oct 2007 – Jul 2012 · 4 yrs 10 mos

Education

Master in Sociology, Specialisation: Statistics and Quantitative Methods · University of Warsaw, Institute of Sociology (IS)2003 – 2012

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